Oocyte Retrieval

Since 1970, oocyte retrieval methods have gone through different stages. The first procedure used by Steptoe and Edwards for oocyte retrieval was laparoscopy instead of laparotomy.

The laparoscopic method evolved with time, having a success rate of up to 70% (retrieved oocytes per ovarian follicles) in most centers. On the other hand, general anesthesia, skilled surgeons and special instrumentation were needed.

Around 1980, the procedure was simplified, by using a new transvaginal technique of oocyte retrieval under ultrasound guidance. This technique is simpler and allows superior ultrasound imaging of the great pelvic vessels and ovarian follicles.

Transvaginal oocyte retrieval is scheduled 35- 36 hours after the b-hCG injection, and is performed in a specially designed operating room, so that proper collection, evaluation and fertilization of oocytes is ensured.

Oocytes are usually retrieved after the patient is placed under intravenous sedation under the guidance of a qualified anesthesiologist. The procedure is painless. In case of a natural cycle, or when a small number of follicles is present, the procedure can be done without sedation.

During the procedure the gynecologist, using a special needle attached to the vaginal ultrasound probe,aspirates the follicular fluid from the follicles. The fluid is collected and the embryologists then search for the oocytes.

The number of oocytes retrieved may differ from the number of follicles aspirated in the stimulated cycle because sometimes not every follicle contains an oocyte. A percentage of retrieved oocytes around 70-80% is considered satisfactory.

The collected oocytes are immediately processed and transferred to special culture media in incubators, where they remain for a short period of time.